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Ndfeb magnet plating the development trend of new technology _ ndfeb strong magnet manufacturers

by:Newland     2020-04-04
Of ndfeb magnet material microstructure analysis shows that it exists three phase = Nd2Fe14B phase; Rich Nd phase; Rich phase B. Among them, the Nd2Fe14B is main phase, grain in polygon; Rich B phase, exist in isolation block or makings; Rich Nd phase, along the grain boundary or corner office on grain boundary distribution; The microstructure is necessary to obtain good magnetic, but from the point of view of corrosion resistance is bad, this is due to different phase due to the potential difference between the cause of the electrochemical corrosion. In three phases, the corrosion rate of rich phase B is the fastest, second, is the rich Nd phase, the slowest Nd2Fe14B phase. Rich and rich Nd B relative to Nd2Fe14B phase as the anode, and compared Nd2Fe14B rich B and rich Nd phase volume is much bigger. In this way, leading to the corrosion of the small anode bear the large current, make the rich and rich Nd phase B are corroded at the rate of growth, corrosion is along the boundary of the rich and rich Nd phase B, on the macro magnet pulverization, metal neodymium in ndfeb material content is higher, around 15%, the chemical properties of neodymium is very lively, easy to oxidation, when there is aerobic, neodymium oxide formation, therefore, to prevent ndfeb magnets by oxidation in the process of manufacturing and processing.   In recent years, with the development of technology, ndfeb magnetic can also in unceasing enhancement, high magnetic energy product and high coercive force, high temperature and low cost is always the direction of the research institutions and manufacturers. New products through adjusting formula and manufacturing process to obtain material, formula of the improved mostly to add a variety of other elements, the anticorrosive material is bad, although some add elements can improve the corrosion resistance of materials, such as a small amount of Co elements, but for most of the elements is damaging to improve resistance to corrosion. Rare earth elements in the ore deposit is often in the nature symbiotic, separation and purification to single neodymium is more troublesome, but some mixed rare earth raw materials production, such as neodymium praseodymium alloys, in does not affect the magnetic under the premise of lower cost of ndfeb material can be obtained, but all of these give a summary of anticorrosive work put forward higher requirements. When the magnet surface grain boundary corrosion can cause ndfeb magnet surface coating porosity increases, causing loss of damp and hot test, which resulted in increased surface magnetic loss after plating. So under the condition of traditional electroplating process, electroplating by high temperature and high humidity ( Temperature & 85 deg; C, humidity 85%) Test after 24 h magnetic loss of 15% ~ 18%. And after the introduction of the technological process by high temperature and high humidity ( Temperature & 85 deg; C, humidity 85%) Test after 24 h magnetic loss & lt; 5%.     For the above sintered ndfeb permanent magnet under the condition of existing electroplating process, electroplating by high temperature and high humidity ( Temperature & 85 deg; C, humidity 85%) Test after 24 h magnetic loss is as high as 15% ~ 18%. The lastest developed a can reduce under the condition of high temperature and high humidity ndfeb permanent magnet magnetic loss process method.   The technical scheme for new technology: & ensp; Including chamfering of ndfeb permanent magnet, degreasing, pickling, activation pretreatment process, electroplating process, electroplating processing craft, electroplating process including from top to bottom plating nickel plating, in turn the middle layer of copper and nickel plating, nickel plating thickness of bottom 5 ~ 10 & mu; M, middle copper layer thickness is 5 ~ 7 & mu; 5 ~ 10 m between, outside nickel plating thickness & mu; m。 Electroplating process of bottom layer of nickel plating solution composition NiSO4 & bull; 6H20260〜 300g/L,NiCL240〜50g/L,H3B0340〜50g/L,pH=4. 1 ~ 4. 5, current density: 0. 08〜O. 24A/dm2;   The beneficial effects of the new technology for: & ensp; Sintered ndfeb permanent magnet products after plating the damp and hot test ability is greatly increased. After the high temperature and high humidity ( Temperature & 85 deg; C, humidity 85%) Test after 24 h magnetic loss & lt; 5%. Significantly improve the quality of the nickel plating layer and the properties of sintered ndfeb permanent magnet materials, so that the ndfeb permanent magnet material has a more broad application prospects.
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